1// Copyright (c) 2012, Google Inc.
2// All rights reserved.
3//
4// Redistribution and use in source and binary forms, with or without
5// modification, are permitted provided that the following conditions are
6// met:
7//
8//     * Redistributions of source code must retain the above copyright
9// notice, this list of conditions and the following disclaimer.
10//     * Redistributions in binary form must reproduce the above
11// copyright notice, this list of conditions and the following disclaimer
12// in the documentation and/or other materials provided with the
13// distribution.
14//     * Neither the name of Google Inc. nor the names of its
15// contributors may be used to endorse or promote products derived from
16// this software without specific prior written permission.
17//
18// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30// This source file provides replacements for libc functions that we need. If
31// we call the libc functions directly we risk crashing in the dynamic linker
32// as it tries to resolve uncached PLT entries.
33
34#include "common/linux/linux_libc_support.h"
35
36#include <stddef.h>
37
38extern "C" {
39
40size_t my_strlen(const char* s) {
41  size_t len = 0;
42  while (*s++) len++;
43  return len;
44}
45
46int my_strcmp(const char* a, const char* b) {
47  for (;;) {
48    if (*a < *b)
49      return -1;
50    else if (*a > *b)
51      return 1;
52    else if (*a == 0)
53      return 0;
54    a++;
55    b++;
56  }
57}
58
59int my_strncmp(const char* a, const char* b, size_t len) {
60  for (size_t i = 0; i < len; ++i) {
61    if (*a < *b)
62      return -1;
63    else if (*a > *b)
64      return 1;
65    else if (*a == 0)
66      return 0;
67    a++;
68    b++;
69  }
70
71  return 0;
72}
73
74// Parse a non-negative integer.
75//   result: (output) the resulting non-negative integer
76//   s: a NUL terminated string
77// Return true iff successful.
78bool my_strtoui(int* result, const char* s) {
79  if (*s == 0)
80    return false;
81  int r = 0;
82  for (;; s++) {
83    if (*s == 0)
84      break;
85    const int old_r = r;
86    r *= 10;
87    if (*s < '0' || *s > '9')
88      return false;
89    r += *s - '0';
90    if (r < old_r)
91      return false;
92  }
93
94  *result = r;
95  return true;
96}
97
98// Return the length of the given unsigned integer when expressed in base 10.
99unsigned my_uint_len(uintmax_t i) {
100  if (!i)
101    return 1;
102
103  int len = 0;
104  while (i) {
105    len++;
106    i /= 10;
107  }
108
109  return len;
110}
111
112// Convert an unsigned integer to a string
113//   output: (output) the resulting string is written here. This buffer must be
114//     large enough to hold the resulting string. Call |my_uint_len| to get the
115//     required length.
116//   i: the unsigned integer to serialise.
117//   i_len: the length of the integer in base 10 (see |my_uint_len|).
118void my_uitos(char* output, uintmax_t i, unsigned i_len) {
119  for (unsigned index = i_len; index; --index, i /= 10)
120    output[index - 1] = '0' + (i % 10);
121}
122
123const char* my_strchr(const char* haystack, char needle) {
124  while (*haystack && *haystack != needle)
125    haystack++;
126  if (*haystack == needle)
127    return haystack;
128  return (const char*) 0;
129}
130
131const char* my_strrchr(const char* haystack, char needle) {
132  const char* ret = NULL;
133  while (*haystack) {
134    if (*haystack == needle)
135      ret = haystack;
136    haystack++;
137  }
138  return ret;
139}
140
141void* my_memchr(const void* src, int needle, size_t src_len) {
142  const unsigned char* p = (const unsigned char*)src;
143  const unsigned char* p_end = p + src_len;
144  for (; p < p_end; ++p) {
145    if (*p == needle)
146      return (void*)p;
147  }
148  return NULL;
149}
150
151// Read a hex value
152//   result: (output) the resulting value
153//   s: a string
154// Returns a pointer to the first invalid charactor.
155const char* my_read_hex_ptr(uintptr_t* result, const char* s) {
156  uintptr_t r = 0;
157
158  for (;; ++s) {
159    if (*s >= '0' && *s <= '9') {
160      r <<= 4;
161      r += *s - '0';
162    } else if (*s >= 'a' && *s <= 'f') {
163      r <<= 4;
164      r += (*s - 'a') + 10;
165    } else if (*s >= 'A' && *s <= 'F') {
166      r <<= 4;
167      r += (*s - 'A') + 10;
168    } else {
169      break;
170    }
171  }
172
173  *result = r;
174  return s;
175}
176
177const char* my_read_decimal_ptr(uintptr_t* result, const char* s) {
178  uintptr_t r = 0;
179
180  for (;; ++s) {
181    if (*s >= '0' && *s <= '9') {
182      r *= 10;
183      r += *s - '0';
184    } else {
185      break;
186    }
187  }
188  *result = r;
189  return s;
190}
191
192void my_memset(void* ip, char c, size_t len) {
193  char* p = (char *) ip;
194  while (len--)
195    *p++ = c;
196}
197
198size_t my_strlcpy(char* s1, const char* s2, size_t len) {
199  size_t pos1 = 0;
200  size_t pos2 = 0;
201
202  while (s2[pos2] != '\0') {
203    if (pos1 + 1 < len) {
204      s1[pos1] = s2[pos2];
205      pos1++;
206    }
207    pos2++;
208  }
209  if (len > 0)
210    s1[pos1] = '\0';
211
212  return pos2;
213}
214
215size_t my_strlcat(char* s1, const char* s2, size_t len) {
216  size_t pos1 = 0;
217
218  while (pos1 < len && s1[pos1] != '\0')
219    pos1++;
220
221  if (pos1 == len)
222    return pos1;
223
224  return pos1 + my_strlcpy(s1 + pos1, s2, len - pos1);
225}
226
227int my_isspace(int ch) {
228  // Matches the C locale.
229  const char spaces[] = " \t\f\n\r\t\v";
230  for (size_t i = 0; i < sizeof(spaces); i++) {
231    if (ch == spaces[i])
232      return 1;
233  }
234  return 0;
235}
236
237}  // extern "C"
238